 /*******************************************************************************
  * Copyright (c) 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  ******************************************************************************/

 package org.eclipse.ui.navigator.resources;

 import java.util.Iterator ;
 import java.util.LinkedHashSet ;
 import java.util.Set ;

 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.swt.dnd.DragSourceEvent;
 import org.eclipse.swt.dnd.FileTransfer;
 import org.eclipse.swt.dnd.Transfer;
 import org.eclipse.ui.navigator.CommonDragAdapterAssistant;
 import org.eclipse.ui.navigator.INavigatorDnDService;
 import org.eclipse.ui.part.ResourceTransfer;
 import org.eclipse.ui.views.navigator.LocalSelectionTransfer;

 /**
  * Clients may reference this class in the <b>dragAssistant</b> element of a
  * <b>org.eclipse.ui.navigator.viewer</b> extension point.
  *
  * <p>
  * Clients may not extend or instantiate this class for any purpose other than
  * {@link INavigatorDnDService#bindDragAssistant(CommonDragAdapterAssistant)}.
  * Clients may have no direct dependencies on the contract of this class.
  * </p>
  *
  * @since 3.2
  *
  */
 public final class ResourceDragAdapterAssistant extends
         CommonDragAdapterAssistant {

     private static final boolean DEBUG = false;

     private static final Transfer[] SUPPORTED_TRANSFERS = new Transfer[] {
             ResourceTransfer.getInstance(),
             LocalSelectionTransfer.getInstance(), FileTransfer.getInstance() };

     private static final Class IRESOURCE_TYPE = IResource.class;

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.navigator.CommonDragAdapterAssistant#getSupportedTransferTypes()
      */
     public Transfer[] getSupportedTransferTypes() {
         return SUPPORTED_TRANSFERS;
     }

     /*
      * (non-Javadoc)
      *
      * @see org.eclipse.ui.navigator.CommonDragAdapterAssistant#setDragData(org.eclipse.swt.dnd.DragSourceEvent,
      * org.eclipse.jface.viewers.IStructuredSelection)
      */
     public boolean setDragData(DragSourceEvent anEvent,
             IStructuredSelection aSelection) {

         if (LocalSelectionTransfer.getInstance().isSupportedType(
                 anEvent.dataType)) {
             anEvent.data = aSelection;
             if (DEBUG) {
                 System.out
                         .println("ResourceDragAdapterAssistant.dragSetData set LocalSelectionTransfer"); //$NON-NLS-1$
 }
             return true;
         } else if (ResourceTransfer.getInstance().isSupportedType(
                 anEvent.dataType)) {
             anEvent.data = getSelectedResources(aSelection);
             if (DEBUG) {
                 System.out
                         .println("ResourceDragAdapterAssistant.dragSetData set ResourceTransfer"); //$NON-NLS-1$
 }
             return true;
         } else if (FileTransfer.getInstance().isSupportedType(anEvent.dataType)) {

             IResource[] resources = getSelectedResources(aSelection);

             // Get the path of each file and set as the drag data
 final int length = resources.length;
             int actualLength = 0;
             String [] fileNames = new String [length];
             for (int i = 0; i < length; i++) {
                 IPath location = resources[i].getLocation();
                 // location may be null. See bug 29491.
 if (location != null) {
                     fileNames[actualLength++] = location.toOSString();
                 }
             }
             if (actualLength > 0) {
                 // was one or more of the locations null?
 if (actualLength < length) {
                     String [] tempFileNames = fileNames;
                     fileNames = new String [actualLength];
                     for (int i = 0; i < actualLength; i++)
                         fileNames[i] = tempFileNames[i];
                 }
                 anEvent.data = fileNames;
     
                 if (DEBUG)
                     System.out
                             .println("ResourceDragAdapterAssistant.dragSetData set FileTransfer"); //$NON-NLS-1$
 return true;
             }
         }
         return false;

     }

     private IResource[] getSelectedResources(IStructuredSelection aSelection) {
         Set resources = new LinkedHashSet ();
         IResource resource = null;
         for (Iterator iter = aSelection.iterator(); iter.hasNext();) {
             Object selected = iter.next();
             resource = adaptToResource(selected);
             if (resource != null) {
                 resources.add(resource);
         }
         }
         return (IResource[]) resources.toArray(new IResource[resources.size()]);
     }

     private IResource adaptToResource(Object selected) {
         IResource resource;
         if (selected instanceof IResource) {
             resource = (IResource) selected;
         } else if (selected instanceof IAdaptable) {
             resource = (IResource) ((IAdaptable) selected)
                     .getAdapter(IRESOURCE_TYPE);
         } else {
             resource = (IResource) Platform.getAdapterManager().getAdapter(
                     selected, IRESOURCE_TYPE);
         }
         return resource;
     }

 }

